1. Field of Invention
The invention relates generally to collapsible containers constructed of paperboard material, and more particularly to reinforcing the container during the manufacturing process and before the container is erected.
2. Description of Background Art
Historically the bulk packaging and transport of certain products has been accomplished through the use of octagon bulk containers. The length and width of these containers are such that they fit a 40".times.48" pallet with the depth of the container determined by the product packaged according to its weight. In addition, liner, medium and flute configuration of these containers is determined by the product being packaged, its weight and the resistance that the package must have to bulge and compression in order to maintain container integrity and shape during container transit. In addition to bulge resistance and in the case where containers are stacked two high during storage and transit, stacking compression required to support double stacking dictates the use of certain liner, medium and flute configurations.
By way of example, consider the use of octagon bulk containers in the poultry industry. This industry utilized basically two types of octagon bulk containers for shipment of chicken frames and bones and for shipment of mechanically deboned meat (MDM). The frames and bones left over from the processing of a chicken are typically shipped to an MDM processor. The bones are dumped into a "grinder" and along with addition of salt and other additives, the end product, a thick flowable meat, is produced and packed into an octagon bulk container for shipping. This product is sold and shipped to companies producing hot dogs, bologna, and other meat items with the MDM meat used as a "filler".
The octagon container used for shipment of the MDM meat is sized, typically 36"-40" deep, to accommodate 2,080 lbs. of this thick flowable meat. Because of the density of this product and the total weight in the bin, processors have typically placed 3-6 straps on the assembled container by hand, prior to filling. These straps are placed on the container to add resistance to bulge and to assist in preventing the container from rupturing at its glue joint, typically the place on a container subject to fail if not properly glued during manufacture. A fallacy in placing these straps exists, in that the strapping material typically used was not intended to resist bulge. Further, when applying the strap by hand, the friction seal typically used to connect the strapping material was not adequate for meeting the demands for preventing container rupture. In addition, the strap friction seal would break as well.
Further, by way of the example presented herein, the thick flowable meat (2,080 lbs.) has a tendency to have the products forming the flowable meat settle toward the bottom of the container, especially after being vibrated during transit. The greatest point of bulge would therefore occur within the bottom half of the container, thus pushing outward against container lower walls and straining the container glue joint. Typically container users, applying their own straps, are not aware that the straps should be placed at strategic intervals in order to provide the greatest resistance at the greatest points of bulge.
In order for the user to pre-apply their own straps to a container, typically they would have to unload a trailer truck of bulk containers shipped in the flat from container manufacturer and stage the unstrapped bulk in an area of their plant, a box room. Then an employee assembles a container in upright position, and using a hand tool, places 3-5 straps around the girth of an assembled container using whatever strapping material is available. The employee stages erected strapped containers in an area accessible to a packing line. The packing line comes to the staging area to secure container for filling.
It should also be noted that in the absence of a friction sealing hand tool, either metal or plastic buckles are typically used to secure the straps. In a food processing environment this introduces a potential hazard and contamination when one of the buckles inadvertently finds its way into the product.
The specification for a container typically requires a container having either triple wall (4 liners; 3 mediums) or laminated (double wall-to-double wall or double wall-to-single wall) construction. Use of these specifications afforded greater bulge resistance due to the actual thickness of combined corrugated materials. In either case, triple wall or laminated container construction, availability is limited due to a minimal amount of container plants having the manufacturing capability to produce containers to these specifications, and economically produce the container.
As described earlier, transport of frames and bones is accomplished through use of a octagon container. Performance requirements for this container are not as stringent as the above described container. When carrying 1200-1800 lbs. of wet frames and bones, which are not nearly as dense as various flowable meats, bulge is not as evident and in most cases straps do not have to be pre-applied for safer transit. What does remain critical to an even greater degree, however, is the performance of the glue joint. Unlike the previous container construction described and not having a plastic liner inserted in all cases as the previous product, the exposure to constant moisture from the bones, and oftentimes ice used during storage of the bones, requires that the glue joint be correctly manufactured. Should the glue joint on these containers rupture, an absolute mess is created that must literally be shoveled up by hand, leading to excess labor costs, disgruntled customers, disgruntled employees, and employees running the risk of injury.
The specifications for these containers typically require then relatively heavy liners and medium of double wall construction (3 liners; 2 mediums) to be impregnated with wax to resist the wet and moisture laden environment to which the container is subjected. Waxing precludes recycling and is neither ecologically nor economically sound.
Another requirement for each the previously described containers is the need for sesame tape. Approximately 3/8" wide, this tape is laminated between the liners and medium of the container during the combining process on a corrugator at a box plant. The placement of 5-8 strands of this tape throughout the depth adds a degree of bulge resistance to the container. If, however, the container ruptures at the glue joint, which is the most common failure, sesame tape does nothing to add to the integrity and safe transit of the packed and filled container.
Although, the octagon shape provides greater resistance to bulge over conventional rectangular or square containers, many octagonal containers do not meet the requirements demanded when used in the examples as cited above. For example, resistance to bulging may occur when flaps on the container bottom do not properly fit or when flaps having typically 3/8" wide slots, include slots with ragged edges due to dull slotting heads. Further, slots can vary in depth into the body of the container creating small openings or fall short of a score line causing tearing when folding. Both conditions weaken bulge resistance in corners of packed container.